1. Field of the Invention
The present invention relates to methods of forming nano-devices, and more particularly, to methods of forming nano-devices using nanostructures having self-assembly characteristics.
2. Description of the Related Art
In general, as semiconductor devices are miniaturized and rendered multi-functional, their design rules also decrease. However, it is difficult to miniaturize semiconductor devices and improve their performance through conventional methods. Therefore, in order to miniaturize semiconductor devices, increase their response speed, and increase the amount of information they can process, nano technology is being applied to semiconductor device fabrication. Here, nano technology refers to technology in which composition, assembly, control, measurement, and/or properties of materials are examined in minute units of atomic or molecular scale requiring a precision of 10−9 m.
Examples of nano technology applied to semiconductor device fabrication include a method of forming a nano-scale inclined structure used in a liquid crystal display and/or a nano print template. In the structure forming method, a semiconductor wafer substrate may include at least one material layer. Photoresist is formed on the substrate, and then exposure and development processes are performed thereon. An anisotropic ion etching process is performed in a direction of largest relative structure inclination on the substrate to remove a non-protective material layer. The remained photoresist cap blocks at least one material layer region. As the ion etching process is performed, an inclined protection region of the material layer is exposed.
However, since the structure forming method includes forming a pattern on the photoresist through the exposure process, it may be difficult to reduce a minimum feature-size of the semiconductor devices due to wavelength limitation of a light source used in the exposure process. In order to solve these problems, next-generation exposure technologies using a short wavelength such as deep ultraviolet (UV), X-rays, or an e-beam, and patterning methods using polymer materials other than photoresist, have been researched.
As an example of nanometer-scale patterning technologies using a light source, a next-generation exposure technique of oxidizing aluminum to form anodized aluminum oxide (AAO) and forming a nanometer-scale pattern using the AAO as a mask has been proposed. In addition, there is also a technique of applying external energy such as an electron beam to form a nanometer-scale pattern on a substrate.
However, the nanometer-scale patterning techniques using a light source or an electron beam may complicate a manufacturing process and increase manufacturing cost of semiconductor devices.
Meanwhile, a technique of forming a nano-structure using a material having self-assembly characteristics like a deoxyribonucleoic acid (DNA) molecule is also being researched to reduce the minimum feature-size of semiconductor devices. For example, a DNA sequence can be changed using self-assembly characteristics, and a DNA nano-structure can be designed using the DNA sequence.
In order to make a nano-device using a DNA molecule, a technique of forming a nano-wire or a nano-electrode is needed. For example, a technique of replacing a metal particle and an ion on the basis of a DNA molecule is needed. Therefore, a nanometer-scale DNA-based nano-wire and a nano-electrode having a nanometer gap can be formed by replacement of a negative charge in a DNA molecular structure with a cation having a different polarity than the negative charge.
In addition, a technique of forming a nano-structure by depositing a thin layer using a two- or three-dimensional nano-structure, and a technique of changing a DNA molecular sequence having self-assembly characteristics to make a desired structure, depositing a thin film, and then transferring it onto a substrate at a desired position to form a nano-structure, are being developed.
However, in the techniques of forming a nano-structure using a two- or three-dimensional DNA nano-structure or by changing a DNA molecular sequence, control of the shape and position of the nano-structure is difficult, and a nano-device manufacturing process is complicated.